1. Field of the Invention
The present invention relates to the field of modern photography, and more particularly to a method and apparatus for single-exposure synthesizing of images on films.
2. Prior Art
Along with scientific development, photographic technology has improved greatly, and the expectation of people, with respect to photograph effects, has improved too. With regard to the synthesized image composing of two images (one prepared image and one instantaneous image) on the same film, such has found favor with a lot of people. This is because it can improve the artistic quality, the memory quality (the impression that it leaves with those who view it), the advertisement quality, and improves the appearance of the resulting image(s).
The conventional method for single-exposure synthesizing of an image is shown on FIG. 1, in which the objective lens 1 represents the objective system of the camera. A bicurvature lens 2, having a flat center portion that conducts the light rays from the instantaneous image through it, is set at the front of the objective lens 1. The circumference portion of the bicurvature lens surrounding the flat center portion is a lens with a certain focal length, to thereby refract the prepared picture 3 light rays so as to project them onto the circumference portion of the film 4, via the objective lens 1, to generate a copy of the prepared image. Meanwhile, the light rays of the outside instantaneous image pass through the central hole 31 of the prepared picture 3, the flat center portion of the bicurvature lens 2 and the objective lens 1 to project onto the central portion of the film 4 to generate a copy of the instantaneous image. Thus, a synthesized image is composed on the film 4.
After studying the above-described method, it is not difficult to find that it has some shortcomings.
1. For obtaining a clear synthesized image composed from a prepared picture and an instantaneous image on the film 4, the bicurvature lens 2 is designed to attach on the front of the objective lens 1 of the camera so that the composing lens becomes a bifocal lens. The light rays from the instantaneous image are cast onto the center of the film 4 via the flat center portion of the bicurvature lens 2. But, if the flat center portion is displaced slightly in a radial direction, it will affect the resolution of the composed picture, as the prepared picture light rays will not be cast onto the circumferential portion of the film 4 exactly as originally expected by the designer. Some of that image will be diffused across the objective lens 1 onto the center portion of the film 4, through the flat center portion of the bicurvature lens 2, unnecessarily scattering light to disturb the instantaneous image at the center portion of the film 4. As shown on FIG. 1, the point A of the prepared picture would be expected to be copied on point Axe2x80x2 of the film 4 via the objective lens 1 by the bicurvature lens 2. But, it actually is diffused somewhere at the center portion of the film 4, like Bxe2x80x2 or Cxe2x80x2, through the center of the objective lens 1 to cause a fuzzy image.
2. Due to the differences in curvature of the center portion and the circumferential portion of the bicurvature lens 2, and the high degree of concentricity required, the manufacturing of the bicurvature lens 2 becomes very difficult, so that the production cost of the device is very high.
3. With respect to the composing image technology, the principal axis of the bicurvature lens 2 must be maintained coincident with the principal axis of the objective lens 1, thereby demanding a very critical assembling technique requiring a high degree of expertise and a high accuracy of location, so as to further increase the production costs.
4. Because various models of cameras each have different objective lens with different focal distance, each different objective lens 1 requires a different size of bicurvature lens 2. Hence, one size of the dual-duty synthesized image attachment may suit only one model of camera, providing little or no versatility.
It is therefore a main object of the present invention to provide a method for forming single-exposure synthesized images that can shoot a clear and high resolution synthesized picture.
It is another object of the present invention to provide an apparatus for forming a single-exposure synthesized image designed according to the above-referenced method, that can be manufactured at a low production cost, and assembled easily, and easily attached on any model of camera.
For archiving those objects, the present invention locates a reflective mirror having a central hole in front of the objective lens, and a prepared picture, also having a central hole or a transparent central portion, located at a proper position between the reflective mirror and the objective lens. Wherein, the reflecting side of the reflective mirror faces toward the picture and the objective lens, so that the light rays from the prepared picture can be reflected to the circumferential portion of the film, to form the image expected from the prepared picture via the objective lens. Meanwhile, the image light rays from the subject being photographed pass through the center hole of the reflective mirror, the central hole or the central transparent portion of the preparation picture and the objective lens to generate an image on the central portion of the film.
In the above-mentioned method, the principal axis of the reflective mirror has to coincide with the principal axis of the objective lens. The prepared picture has to be located at the principal focus of the reflective mirror, and substantially perpendicular to the principal axis of the reflective mirror.
The center point of the central hole or the central transparent portion of the preparation picture and the center point of the central hole of the reflective mirror have to be on the principal axis of the objective lens.
For achieving the method for forming a single-exposure synthesized image, the corresponding apparatus includes a prepared picture having a central hole or a central transparent portion, and a reflective mirror having a central hole. The reflective mirror is located in the front of the prepared picture with the reflecting surface facing the picture. The prepared picture is located at the proper position between the objective lens and the reflective mirror. The prepared picture and the reflective mirror are integrated into an attaching box.
In the apparatus, the reflective mirror can be either a spherical mirror or a non-spherical mirror.
The central hole or the central transparent portion of the prepared picture is the same as the central hole of the reflective mirror in the shape, and proportion. The box is composed of transparent plates.
When a photograph is taken by pressing the shutter release down, the light rays from the prepared picture generate a virtual image on the reflective mirror. The virtual image surrounding the central hole of the mirror is projected onto a circumferential portion of the film to appear as the prepared picture thereon. Meanwhile, the light rays from the subject being photographed pass through the central hole of the reflective mirror and the central hole or the central transparent portion of the prepared picture to be imaged on the central portion of the film via the objective lens, thereby composing a synthesized image.
This invention has advantages when compared with the prior art as follows:
1. The method of photographing with the present invention is the same as the common photographic method. The prepared picture is imaged on the reflecting surface of the reflective mirror to form a virtual image surrounding the image of the subject being photographed, and they are projected onto the same film with the same objective lens, same shutter and same aperture to image a clear picture with high resolution and a good image effect. The central hole acts as a field stop to restrict the range of instantaneous image (that which is being photographed) in size and shape.
2. The present invention does not need attachment to a pre-exposure system and an additional refracting system (like a bicurvature lens), and does not require a change to the inside construction of the camera. It is a feature of the present invention to be a simple structure, easily located, convenient in operation, and have a low production cost.
3. Due to the inclusion of a transparent box, the outside light can pass through the box to light the prepared picture. The prepared picture and the reflective mirror are fixed to the box. The relative positions of the prepared picture and the mirror are fixed too, so that the user can change the picture at will.
4. The individual apparatus can attach on any model of camera without limitation, as the distance to the objective lens will not substantially affect the resolution and enlarging power.